Therapy of malignancy-associated hypercalcemia: 1983

Hypercalcemia is common among patients with cancer and may be due to secretion by tumors of a humoral, calcemic, bone-resorbing factor or, alternatively, to skeletal metastases. In each case, hypercalcemia ultimately results from osteoclastic bone resorption. Therapy should be aimed at (1) reducing or eliminating tumor burden, (2) increasing renal calcium clearance, and (3) inhibiting osteoclastic bone resorption. Hydration with saline infusion and augmentation of calciuresis with furosemide should be the initial modes of therapy in most patients. Oral phosphorus should be used in hypophosphatemic patients. Glucocorticoids, calcitonin, and prostaglandin synthetase inhibitors may be effective in reducing bone resorption in selected patients. Mithramycin reliably induces a fall in serum calcium but long-term use is usually complicated by toxicity. A new class of drugs that inhibit osteoclastic bone resorption, the diphosphonates, is being employed in clinical trials in patients with malignancy-associated hypercalcemia. Results have been particularly promising with dichloromethylene diphosphonate.

Thrombin, a stimulator of bone resorption

It is shown that thrombin (0.1-7 units/ml) stimulates calcium mobilization and bone matrix degradation, as indicated by release of [3H]proline, from cultured calvarial bones. The second finding in this paper, that indomethacin blocks the stimulating effect of thrombin on bone resorption, is consistent with the concept that prostaglandin synthesis may be involved in this process. It is suggested that thrombin is a potential mediator of bone resorption associated with inflammatory and malignant processes.

Exogenous hyperthyroidism with osteoporosis

Symptomatic osteopenia accompanied by subclinical hyperthyroidism developed in three women who were receiving excess thyroid hormone medication. Excessive thyroid replacement therapy resulted in mild hypercalcemia, hyperphosphatemia, and hyperphosphatasemia associated with diffuse skeletal demineralization and multiple fractures. Nondecalcified sections of double tetracycline-labeled iliac crest bone showed an accelerated rate of bone turnover with marked osteoclastosis and resorption of the cortical as well as the trabecular bone, typical of endogenous hyperthyroidism. Since thyroid hormones are among the most frequently prescribed medications, bone loss caused by exogenous hyperthyroidism may be more common than previously recognized.

Effects of dichloromethylene diphosphonate in women with breast carcinoma metastatic to the skeleton

Ten women with skeletal metastases from breast carcinoma received dichloromethylene diphosphonate (Cl2MDP), an inhibitor of osteoclast function, in a placebo-controlled, double-blind, crossover study. Eight of these patients had either hypercalcemia or hypercalciuria, and all 10 had elevated urinary hydroxyproline levels as evidence of active skeletal disease. Eight patients had moderate to severe bone pain. After eight weeks of oral dichloromethylene diphosphonate treatment (3,200 mg per day), either preceded by or followed by an eight-week placebo period, seven of eight patients with hypercalciuria had significant reductions in urinary calcium levels, and nine of 10 had reductions in urinary hydroxyproline levels (significant in eight) when the dichloromethylene diphosphonate treatment periods were compared with prestudy or placebo periods. Additionally, seven of eight subjects had decreased pain with dichloromethylene diphosphonate. There were no adverse effects other than transient diarrhea in some patients. We conclude that oral dichloromethylene diphosphonate can significantly inhibit osteoclast-mediated bone destruction in patients with bone metastases from breast cancer.

Drug treatment of primary hyperparathyroidism: use of clodronate disodium

Clodronate disodium (dichloromethylene diphosphonate), a specific inhibitor of bone resorption, was given by mouth (1.0-3.2 g daily) to nine patients with primary hyperparathyroidism for two to 32 weeks so that its clinical and metabolic effects could be evaluated. Bone resorption decreased in all patients as judged by a fall in the fasting urinary calcium to creatinine and hydroxyproline to creatinine ratios. Serum calcium concentration was increased in all patients before treatment and fell in response to treatment to values near the upper end of the normal range. Hypercalcaemia and hypercalciuria recurred when treatment was stopped. In three patients treated for longer than 19 weeks clodronate failed to sustain the reduction in serum calcium concentration but the concentration remained below pretreatment values. These results suggest that clodronate may be of use in the medical management of primary hyperparathyroidism, particularly in patients in whom suppression of bone disease is desirable before surgery or in whom surgery is contraindicated.

Platelet-derived growth factor stimulates bone resorption by monocyte monolayers

Resorption of devitalized bone particles by monocytes grown in culture was stimulated by platelet-derived growth factor (PDGF) in a dose-dependent manner. Bone resorption in response to PDGF was time-dependent with a significant increase over control cultures evident by 72 hours. These data are the first to demonstrate stimulation of bone resorption by PDGF in a specific cell type known to resorb bone in vivo and in vitro.

Zinc-induced hypocalcemia and bone resorption in rats

The changes of calcium levels in serum and in the femur were examined in rats administered oral doses of zinc sulfate (0.1, 1.0, and 10 mg Zn/100 g body weight) for 3 days. All doses of zinc caused significant decreases in calcium levels in serum and in the femoral diaphysis and epiphysis. The decrease in these femoral calcium levels was seen 1 day after administration of zinc (10 mg/100 g). Furthermore, time course studies of the effect of zinc administration showed that, at 1 hr after zinc administration, calcium levels in serum and in femoral epiphysis but not in diaphysis were significantly decreased. In thyroparathyroidectomized rats, however, no significant decrease of the epiphyseal calcium was observed by administration of zinc (10 mg Zn/100 g), but the serum calcium level was significantly lowered. Zinc administration to intact rats caused a significant increase in acid phosphatase activity in the femoral epiphysis but not in the diaphysis. This increase was clearly prevented by thyroparathyroidectomy. Accumulations of zinc in the femoral epiphysis and diaphysis after zinc administration was not significantly altered by thyroparathyroidectomy. These results suggest that zinc-induced hypocalcemia may cause bone resorption which is primarily mediated by the action of the parathyroid hormone and it is related to calcium homeostasis in rats.

Inhibition of bone resorption in tissue culture by H1-receptor antagonists

Mouse bone culture studies show that several representative H1-receptor antagonists, promethazine hydrochloride, pyrilamine maleate, tripelennamine hydrochloride, and diphenhydramine hydrochloride, inhibit parathyroid extract-stimulated bone resorption. The H2-receptor antagonists, metiamide and cimetidine, are ineffective. In view of the finding that histamine and histamine agonists did not stimulate bone resorption, it is unlikely that histamine receptors are involved in mediating parathyroid extract-stimulated bone resorption. Because H1-receptor antagonists bind to phospholipids and have been shown to influence membrane structure and function, it is suggested that they inhibit bone resorption by a mechanism that depends on their membrane-stabilizing effect.

[Role of calcitonin in pregnant rats : interaction with 1,25-dihydroxycholecalciferol on fetal bone resorption in vivo/in vitro]

We studied in pregnant Rat the effect of 1,25-dihydroxycholecalciferol (1,25(OH)2D3) alone or associated with calcitonin on fetal bone resorption measured by organ culture. 1,25(OH)2D3 (0.1 microgram per day) reduced fetal weight and increased fetal bone resorption. Calcitonin (30 mU/hr.) alone had no significant effects but, associated with 1,25(OH)2D3, it protected mother and foetus against the effect of the vitamin D3 metabolite.

Structure-activity relationships of various bisphosphonates

A variety of bisphosphonates with aliphatic side chains of increasing length, as well as 3-amino-1-hydroxypropylidene-1,1-bisphosphonate (AHPrBP, formerly APD), dichloromethylene-bisphosphonate (Cl2MBP, formerly Cl2MDP), and dibromomethylene bisphosphonate (Br2MBP, formerly Br2MDP), were compared in vitro and in vivo to find (a) a possible relationship between structure and activity in order to give some indication about their mechanism(s) of action on bone and (b) the most efficient and safe compound having an effect on bone resorption. Some relationship was found between inhibition of calcium phosphate precipitation in vitro and of mineralization in vivo. No correlation existed, however, between any parameter measured and bone resorption. The number of calvaria cells in culture was decreased by compounds with a chain length greater than 5-C, by AHPrBP, Cl2MBP, and Br2MBP. Lactate production by these cells in vitro was increased by the long chain bisphosphonates and AHPrBP, and was decreased by Cl2MBP. No good correlation existed between the inhibition of bone resorption measured in vitro on calvaria and that seen in vivo on rat tibiae metaphyses. The latter was inhibited the most efficiently by the bisphosphonates longer than 5-C and by AHPrBP; these were 10 times more effective than Cl2MBP. Taking into account all factors, 1-hydroxypentylidene-1,1-bisphosphonate and AHPrBP seem to be the most active compounds to inhibit bone resorption.

Comparison of fetal rat limb bones and neonatal mouse calvaria: effects of parathyroid hormone and 1,25-dihydroxyvitamin D3

The relative responses of fetal rat limb bones and neonatal mouse calvaria to parathyroid hormone (PTH) and 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) were examined in organ culture. Limb bones were cultured in dishes in BGJ + 1 mg/ml bovine serum albumin (bSA) or DMEM + 15% heat-inactivated horse serum (hS). Calvaria were either cultured in dishes with one of the above two media or in roller tubes in DMEM + hS. The order of sensitivity to PTH was: calvaria in roller tubes greater than limb bones in dishes in DMEM + hS greater than limb bones in dishes in BGJ + bSA greater than or equal to calvaria in dishes in DMEM + hS greater than calvaria in dishes in BGJ + bSA. The most sensitive system (i.e., calvaria in roller tubes) showed significant resorption in response to 10(-10)M PTH at 48 h. The least sensitive system did not respond to 3 X 10(-8)M PTH after the same length of time. The greater response in DMEM + hS compared with BGJ + bSA appeared to be due to the protein component of the medium. The order of sensitivity to 1,25(OH)2D3 was: calvaria in roller tubes = long bones in culture dishes in BGJ + bSA greater than long bones in culture dishes in DMEM + hS greater than calvaria in dishes in DMEM + hS greater than calvaria in dishes in BGJ + bSA. The most sensitive systems showed resorption in response to 10(-11)M 1,25(OH)2D3 by 72 h. The least sensitive system failed to respond to 10(-9)M 1,25(OH)2D3 after the same length of time. The nature of the protein constituent did not seem to influence the response of the limb bones to 1,25(OH)2D3. The results indicated that although the responses of the two bone systems to the calcemic hormones were qualitatively similar, media and culture conditions could markedly affect the sensitivity.

Drug and hormone effects on calcium release from bone

The mobilization of calcium from the bone to the extracellular fluid proceeds in parallel with the dissolution of bone matrix, and is subject to the same influences. The role of circulating hormones has been discussed, and the importance of the skeleton as a store of calcium, even though skeletal calcium release is a relatively slow process in maturity. The major circulating hormones stimulating the processes are parathyroid hormone, 1,25-dihydroxyvitamin D3, and epidermal growth factor related substances. These represent three different classes of hormone with respect to their initial mechanisms of action. The most potent known hormonal inhibitor of bone resorption is the peptide, calcitonin, which acts directly upon the osteoclasts to inhibit their activity and generation. Local factors are undoubtedly important in the regulation of bone resorption, especially the prostaglandins. Prostaglandin E2 is the most potent bone resorber of the arachidonic acid metabolites, and is much more likely to be important locally than as a circulating factor especially in disease states such as metastatic bone cancer and arthritis. In understanding the ways in which drugs can influence bone mineral release it is important to appreciate how bone cells interact to resorb mineral and matrix. In this review the view is presented that cells of the osteoblast lineage (perhaps at the stage of osteocytes, or 'lining' cells) are the prime target of the resorbing hormones. Once having been acted upon, they initiate events which result in activation of osteoclasts. If this involves the passage of a message from osteoblast/osteocyte to osteoclast, it will be important to define this in further research.

Inhibition of bone resorption and increased incorporation of 3H-glucosamine into hyaluronate in bone organ cultures treated with dibutyryl cyclic AMP and colchicine

Addition of dibutyryl adenosine 3':5'-monophosphate (DBCAMP), colchicine or dbcAMP/colchicine to bone organ cultures markedly inhibited bone resorption. Calvaria of newborn mice labeled with 45Ca 3 days before sacrifice were removed and cultured in medium containing 3H-glucosamine. Both agents alone and in combination inhibited 45Ca release. DEAE-cellulose chromatography of the papain-digested medium and bone resolved the 3H-glucosamine-labeled macromolecular material into four peaks. A marked increase in radioactivity was observed in the hyaluronate fraction (peak III) of the chromatographed bone samples. The results indicate that dbcAMP does not mimic the effect of parathyroid hormone on bone resorption, but that it is similar to colchicine in both the inhibition of bone resorption and the increased incorporation of 3H-glucosamine into hyaluronate. Although the role of hyaluronate, if any, in this experimental system remain elusive, the increased radioactivity associated with the hyaluronate fraction may be due to decreased degradation resulting from decreased hyaluronidase synthesis.

Inhibition of bone resorption by difluoromethylene diphosphonate in organ culture

A newly synthesized diphosphonate, difluoromethylene diphosphonate (F2MDP), was studied for its effects on bone resorption, as measured by the release of previously incorporated 45Ca. F2MDP (10 microM to 1000 microM) effectively inhibited both unstimulated and parathyroid hormone-stimulated resorption, and the amount of 45Ca release decreased with time. Dichloromethylene diphosphonate (Cl2MDP) and ethane-1-hydroxyl-1, 1-diphosphonate (EHDP) inhibited resorption to similar extents with two exceptions: At concentrations of 10 microM and 100 microM, F2MDP was more effective than EHDP and less effective than Cl2MDP. No greater inhibition was observed when bones had been stimulated with PTH prior to the addition of F2MDP. In addition, bones treated with F2MDP only during the first half of the incubation period exhibited reductions in the amount of 45Ca released during the second half similar to that observed when F2MDP was continuously in the medium, indicating a prolonged effect. Morphologic alterations of osteoclasts suggestive of cell degeneration were observed in F2MDP-treated bones, which were similar to those observed in bones treated with Cl2MDP and EHDP. Due to the presence of fluorine, F2MDP may be useful as an experimental tool to investigate the mode of action of all diphosphonates, in addition to its possible use as a therapeutic agent for diseases of increased bone resorption.

Fluoride ingestion during multiple pregnancies and lactations: microscopic observations on bone of the rat

Female rats were given 150 ppm fluoride in the drinking water during three successive pregnancy and lactation periods; the femoral diaphyses were then examined for morphological alterations by light and scanning electron microscopy to determine the influence of fluoride ingestion during multiple pregnancies and lactations. The periosteal surface was dominated by areas of woven bone formation with some prolonged resting areas around osteocyte lacunae. The endosteal surface consisted mainly of areas of active bone resorption with some areas of bone formation. The interior of the cortex was characterized by numerous resorption cavities and remodeling in secondary Haversian systems. Fluoride, by the nature of its incorporation into bone crystals and by its direct cytotoxic effect on bone resorbing cells, reduces the availability of calcium from bone. It appears that fluoride ingestion during lactation created a heightened state of calcium homeostatic stress. As a result, bone mineral was mobilized by resorption of the endosteal surface and by cavitation of the interior of the cortex. Secondary hyperparathyroidism is thought to play an integral part in an attempt to maintain calcium homeostasis.

Calcitonin and calcium therapy in an infant with osteogenesis imperfecta congenita

Calcitonin has been helpful in the treatment of osteogenesis imperfecta tarda inhibiting bone mineral resorption. The experience with salmon calcitonin in the early treatment of osteogenesis imperfecta congenita is very limited. Here we report an infant with this disorder treated with calcitonin from 3 to 15 months of age with clinical and radiographic improvement.

Influence of aluminium on the effect of 1 alpha (OH)D3 on renal osteodystrophy

The influence of aluminium in dialysate on the effects of 1 alpha (OH)3 on hemodialyzed hypocalcemic patients with end-stage renal failure, was studied during a 24- to 42-month period. 51 hypocalcemic patients were divided into two groups; group 1 consisted of 28 patients who were dialyzed using dialysate prepared from reverse osmosed water; the 23 patients in group 2 used dialysate prepared from softened water. Aluminium concentration in the dialysate used for group 1 was less than the detectable limit (10 micrograms/l) in twelve times determinations, while that for group 2 was 23.1 +/- 9.2 micrograms/l (mean +/- SD, n = 14). By the administration of 1 alpha (OH)D3, the serum concentration of calcium was increased, and that of iPTH and alkaline phosphatase activity was decreased in both groups. Subperiosteal resorption of the finger bone, evaluated by Jensen's criteria, was significantly improved in group 1, while there was no improvement in group 2. Serum aluminium concentration in the patients of group 1 and group 2 were 46.6 +/- 6.3 and 84.7 +/- 13.9 micrograms/l, respectively, and the concentration of the latter was significantly higher than that of the former (p less than 0.01). It was also shown that there is a positive correlation between the extent of subperiosteal resorption and the concentration of aluminum in serum. Serum aluminium concentration and bone aluminium content were increased according to the duration of hemodialysis in the patients who were dialyzed using dialysate from softened water, while there was no correlation between the duration of hemodialysis and serum aluminium concentration for the patients of group 1.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of prostaglandins on experimental tooth movement in monkeys (Macaca fuscata)

Local administrations of prostaglandins E1 or E2 combined with orthodontic tooth movement can approximately double the rate of tooth movement in monkeys compared to that of the control. Macroscopically, no side-effect was observed in the gingiva and associated structures.

Influence of diphenylhydantoin on isotope release and bone enzymes in vitro

The acute effect of diphenylhydantoin isotope release in an in vitro system using mouse calvaries was studied. A depressive effect on bone resorption was found involving radioactive calcium as well as tritiated proline. Bone resorption and formation were further investigated by semiquantitative histochemistry. Depressed activity of both alkaline and acid phosphatase was found, indicating a direct inhibitory effect of diphenylhydantoin on bone turnover.

Interaction between amrinone and parathyroid hormone on bone in culture

The cardiotonic agent amrinone has been postulated to directly affect Na-Ca exchange. Because stimulated bone resorption has been proposed to require Na-Ca exchange, we examined the effects of amrinone on bone. Amrinone inhibited release of Ca from neonatal mouse calvaria in organ culture stimulated by parathyroid hormone (PTH), 1,25-dihydroxyvitamin d3, or prostaglandin E2. Inhibition was dose dependent and maximal at 2 X 10(-4) M. The effect of amrinone differed from the inhibitory effects of calcitonin, ouabain, or nigericin in that 1) 6-h exposure to amrinone alone prevented the effect of subsequently added PTH; 2) amrinone was only partially effective if added after resorption was initiated by 24-h treatment with PTH; 3) coincubation with amrinone and PTH during the first 48 h of culture allowed for a response to PTH after amrinone was removed; no such protection by a stimulator occurred with ouabain or nigericin. Also submaximal concentrations of amrinone plus calcitonin, ouabain, or nigericin gave greater than additive inhibition of Ca release. Amrinone had no effect on basal bone cAMP or on the acute stimulation of cAMP by PTH. The results suggest that amrinone could have a more direct interaction with the pathway involved in stimulated bone resorption than the other inhibitors.